CLIMATE AND AEROALLERGEN LEVELS IN ASTHMA - A 12 MONTH PROSPECTIVE-STUDY

Background - There is evidence to suggest that changes in weather and airborne fungal spore and pollen counts may affect asthma symptoms. Me thods - The relationship between climate, airborne fungal spore, and p ollen counts and peak expiratory flow rate (PEFR) and asthma symptoms was prospectively investigated in a population of mild to moderate ast hmatic subjects in Blenheim, Mew Zealand. Subjects recorded twice dail y PEFR measurements and asthma symptom scores for up to one year. Spor e and pollen counts were measured two hourly and meteorological data w ere measured hourly. Individual, within person, multiple linear regres sion analyses were conducted, adjusting for auto-correlation, A random effects model was assumed for the individual regression coefficients and weighted estimates of the mean of these coefficients were obtained by the method of maximum likelihood. Results - One hundred and thirty nine asthmatic patients (60% atopic) aged 17-80 years completed the s tudy. Of the weather variables, only temperature showed a small but co nsistent association with PEFR. The mean rise in PEFR for an 8.8 degre es C (2 SD) change in temperature was 0.78% (95% CI 0.44% to 1.11%), a pproximately 3.0 l/min, There was a weak, association between days of high basidiospore counts and increased nocturnal wakening and reliever medication use, Pollen counts showed no consistent association with e ither PEFR or asthma symptoms. Conclusions - The results of this study suggest that the effects of weather and aeroallergens on PEFR and ast hma symptoms in this population are small, and that other causes need to be sought to account for variations in asthma severity and exacerba tions.